Method for the production of compounds containing silicon and nitrogen



UNITED STATES PA-TEN'T- OFFICE.

room) VON BICHOWSKY, or GLENDALEQGALIFORNIA.

METHOD FOR THE PRODUCTION OF COMPOUNDS CONTAINING SILICON AND NITROGEN.

No Qrawing.

My invention relates to the production t compounds containing principally silicon and nitrogen from crude materials, mainly composed of the oxygen containing compounds of silicon and free fromcarbon as such, through the agency of catalytic substances so that temperatures, lower than previously deemed practical, may be employed, thereby avoiding the loss of any appreciable quantity of nitrogen containing material through volatilization.

I have discovered that this resultmay be easily obtained using as a reducing agent carbon, solely in the .form of hydrocarbon gases and in particular the impure mixtures of such'hydrocarbon gases, known as naturalgas, consisting principally of methane and practically free from oxygen, which mixture of hydrocarbon shall hereinafter be referred to as methane. By the use of this gas mixed with nitrogen and in the absence of free'carbon, as a reactive agent, but in the presence of certain activating metallic oxides or combinations of metallic 0X ides, or metals and their alloys, as supple-.

mentarycatalysts, and certain alkalimetal salts, hereinafter. described the'methane is split, at the temperatures employed very completely into carbon and hydrogen, both of which being in the nascent state have an exceptionally high reducing power. these means'thesilicon nitrogen compounds may be prepared in an indirect fired pottery tunnel kiln without the use of saggers, provided the material be -briquetted in a very eflicient and cheap manner, and the employment of the. electric current for either the supplementary or the direct heating of the reactive mass is therefore avoided. Prepared in this way the silicon nitrogen compounds are enabled to compete with ammonia as fertilizing agents, because of their high nitrogen; content. These compounds may be used as a source of other nitrogen "compounds such as the cyanides or ammonia Specification of Letters Patent.

- Patented May 9, 1922.

Application filed February 23, 1921. Serial No. 447,28 1.

and from them pure silica, like may also be recovered.

Having now outlined the purpose of my invention, I will go in greater detail into the method of-carrying it out. The activating metallic oxides, or combination of metallic oxides hereinbefore referred to, may be small amounts of the oxides of such metals alumina and the as vanadium, molybdenum, manganese, al- I uminium, titanium, zirconium, tungsten, niobium, chromium, iron and in general those metals=which will directly combine with nitrogen to form nitrides. These oxides may occur as natural impurities in the siliceous material treated or they may be added, singly or in mixtures, to increase the activity of the siliceous material towards nitrogen. Most valuable for this purpose, however, are the compounds of the iron greup of metals or their alloys which exert a most marked effect in splitting the methane into active carbon and hydrogen. Under this grouping of elements come the 'metals, iron, nickel and cobalt,'which, alone or al- .loved, mas their reduced oxy compounds or mixture of same, with the addition of small amounts of the nitride forming metals already referred to, constitute the activating or catalytic' agents which I most frequently use in carying out this invention. The alkali metal oxygen containing salts maybe either the carbonates, oxides or hydroxides of sodium or potassium or mixtures of these salts with or without the use of similar compounds of the alkaline earth metals, 'or they may be the alkali silicates, aluminates, borates, vanadates, titanates, molybdates, zir- 'conates and the like. By the use of these substances the absorption of nitrogen by'the "impure silicon oxygen containing compounds begins in the neighborhood of 1100 C. and is quite rapid at 1300 centigrade. Above that temperature many of. the metallic alloys begin to melt and if that occurs thetemperature must be lowered lest the reactive mass fuse together, making the separation of'the metallic particles from the nitrides a diflicult mechanical operation. With this point in mind it is best to avoid, as far as possible, any sulphur containing material,

as this element rapidly lowers the resistance of the metals towards high temperature by forming easily fusible sulphides with many of them;

The following examples, in which the parts are given in welght, and the temperature in degrees centigrade, will serve to make clear the exact nature of my invention, which, however, is not limited to the following Example NO. 1.

Mix together very thoroughly A LOO parts of finely ground titaniferous beach sand containing 3 per cent of titanium oxide parts of iron filings'containing 30 per cent ofnickel 2 parts of soda ash 3 parts of water glass 42 B. as a a binder andpress the mixture into briquettes. Stack the latter on cars. and heat them in an indirect fired tunnel kiln for 12 hours at a tem{ perature of 1300". Allow the briquettes to cool in the cooler part of the-kiln in a neutral heated, pass in pure methane,

atmosphere. Upon grinding the" briquettes,

the iron alloy may be recovered magnetic means. The residue consists mainly of titanium nitridesand silicon-nitride. "The reaction that takes place may be represented in part by the following equations-'- The gaseous products escape and may be burned. H

. p ExampZ'eNo. Z. Mix together most thoroughly v parts of fireclay 4E6 parts of finely ground iron oxide 1 partof sodium vanadate 3 parts of Soda ash a the mixture into Place on cars 1n the tunnel kiln andginoisten' and press briquettes. and while or other reducing gas to reduce the iron oxide used to'the metal. When the temperature of the briuettes reaches 1200", pass in a dry mixture of methane and nitrogen 1n equal volumes ina and vanadium may bon as such but in the the briquettes'are being slowly sodium carbonate,

and continue the heating to just below 130.0 for 15 hours. When cold the magnetic iron may be separated out mechanically, the vana dium nitride and unacted upon vanadate may be recoveredby heating w1th sulphuric acid or the mass, irced from iron, may be fused with caustic soda whereby ammonia is evolved in large quantity. The silica, alumbe recovered from the melt by treatment with water, precipitating the alumina from removing the precipitate, then precipitating the silica by acids from the heated solution.

The vanadium will be found in the filtrate,

from this reaction. llclaim: --1. The process of producing compounds containing silicon and nitrogen by heating the solution with CU, and

a silicon oxygen compound containing rea reactive mass containing silica, a metallic -ox1de and a metal of the non group together producing compounds with sodium carbonate, in the absence of carpresence of methane and nitrogen.

3. The process of producing compounds of silicon and nitrogen by heating-a reactive mass composed of silica and a body containing metallic oxide and particles of iron together with sodium carbonate, but free from carbon as a chemical reactive, ata temperamass, and passing over it a mixture of nitrogen andmethane.

- l. The process of producing compounds containing silicon and nitrogen by heating a reactive mass composed of silica andalumini um oxide and particles of metallic iron, and but free from carbon as a chemical reactive ata temperature not exceeding 1300 FOORD VON BTGHQWSKY.

(3., while passing over it a I mixture of nitrogen and .methane.

'ture not exceeding the fusion point of the 

